JP7306552B1 - Laminate separation and collection method - Google Patents

Abstract

A method for separating and recovering a polyolefin resin from a laminate while suppressing suspension (contamination) of a desorbed liquid is provided. Provided is a method for separating and recovering a laminate, which facilitates reuse of the desorbed liquid and reduces the environmental load. The above object is solved by a method for separating and recovering a laminate, comprising a separation step of immersing a laminate comprising at least a first substrate layer, an adhesive layer containing either polyethyleneimine or polybutadiene and having a mass per unit area of 5 to 100 mg/m2 and a polyolefin resin layer in this order in a desorption liquid to separate the polyolefin resin from the laminate, and a recovery step of recovering the separated polyolefin resin. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a laminate separation and recovery method for recovering a polyolefin resin from a laminate having a multilayer structure.

In recent years, it is feared that packaging materials, plastic bottles, and other plastic products made from plastic films discarded or dumped in the ocean as garbage will turn into microplastics and affect marine ecosystems.

In response to such environmental pollution problems, attempts have been made to make recycling easier by changing packaging materials that are normally composed of multiple dissimilar materials into mono-material packaging materials that are composed of a single material such as polyolefin. is being done. However, packaging materials composed only of polyolefin are insufficient in retort resistance and light-shielding properties, and their applications are limited.
In addition, when a monomaterial packaging material to which a printed layer or an adhesive layer is adhered is recycled as it is, the recycled resin obtained is colored, which limits the applications after recycling. Furthermore, since the physical properties of the recycled resin deteriorate due to the components derived from the printed layer and the adhesive layer, it becomes necessary to mix and use petroleum-derived virgin resin, which makes it difficult to improve the recycling rate.

On the other hand, a technique has been developed for obtaining a transparent recycled resin by separating a packaging film composed of a plurality of different materials into single-layer films and removing the printed layer and the adhesive layer.
Regarding the above technology, for example, in Patent Document 1, a laminated film laminated with a reactive adhesive containing a compound having an acidic group, a polyisocyanate composition, and a polyol composition is immersed in an alkaline aqueous solution to form a single layer film. Techniques for separating are disclosed.
In Patent Document 2, a packaging material laminated with a first base material, a printed layer, a polyurethane adhesive layer for detaching the second base material, and the second base material is immersed in an alkaline aqueous solution. 2, a technique for separating and recovering the base material is disclosed.

WO2020/066652 JP 2021-088184 A

That is, in the techniques described in Patent Documents 1 and 2, an adhesive layer, which is a cured product of a reactive adhesive containing a polyol and a polyisocyanate, swells with an alkaline aqueous solution and becomes fine, thereby forming a single-layer film. can be separated and recovered. However, the coating amount of such a reactive adhesive is generally about 1.0 to 5.0 g/m ² , and a large amount of fine pieces of the adhesive layer are generated in the laminate separation process. There is a problem that the liquid is suspended, and the suspended components adhere to the release film, resulting in a decrease in washability.
In addition, when the amount of suspended components in the desorbed liquid increases, the energy required for the filtration and purification processes when reusing the desorbed liquid after use increases, resulting in an increased environmental load.
Accordingly, an object of the present invention is to provide a method for separating and recovering a polyolefin resin from a laminate while suppressing suspension (contamination) of the desorbed liquid. That is, an object of the present invention is to provide a method for separating and recovering a laminate that facilitates reuse of the desorbed liquid and reduces the environmental load.

A method for separating and recovering a laminate according to one aspect of the present invention includes at least a first substrate layer, an adhesive layer containing either polyethyleneimine or polybutadiene and having a mass per unit area of 5 to 100 mg/m ² . and a separation step of immersing a laminate having polyolefin resin layers in this order in a desorption liquid to separate the polyolefin resin from the laminate, and a recovery step of recovering the separated polyolefin resin. do.

A method for separating and recovering a laminate according to an aspect of the present invention is characterized in that the laminate comprises a printed layer between a first substrate layer and an adhesive layer.

In the method for separating and recovering a laminate according to one aspect of the present invention, the content of the curing agent contained in the adhesive forming the adhesive layer is 5% by mass or less based on the solid content mass of the adhesive. characterized by

In the method for separating and recovering a laminate according to one aspect of the present invention, the content of the curing agent contained in the printing ink forming the printing layer is 5% by mass or less based on the solid content mass of the printing ink. Characterized by

A method for separating and recovering a laminate according to an aspect of the present invention is characterized in that the polyolefin resin layer is a layer formed by an extrusion lamination method.

A method for separating and recovering a laminate according to an aspect of the present invention is characterized in that the adhesive layer has a mass per unit area of 10 to 50 mg/m ² .

A method for separating and recovering a laminate according to an aspect of the present invention is characterized in that the adhesive layer contains polyethyleneimine and polybutadiene in a total amount of 50% by mass or more based on the mass of the adhesive layer.

The method for separating and recovering a laminate according to an aspect of the present invention is characterized in that the desorption liquid contains water and a surfactant.

A method for separating and collecting a laminate according to an aspect of the present invention is characterized in that the surfactant is a surfactant having an HLB value of 7 or more.

The method for separating and recovering a laminate according to one aspect of the present invention is characterized in that the desorbing liquid further contains an antifoaming agent having an HLB value of 1 to 3.

A method for separating and recovering a laminate according to an aspect of the present invention is characterized in that the desorbing liquid is an alkaline aqueous solution having a temperature of 40° C. to 90° C. and a pH of 12 or higher.

A laminate separation and recovery method according to an aspect of the present invention is characterized in that the recovery step includes a step of sorting and recovering the separated polyolefin resin by specific gravity separation.

ADVANTAGE OF THE INVENTION By this invention, the method of isolate|separating and collect|recovering polyolefin resins from a laminate laminate can be provided, suppressing suspension (contamination) of a desorption liquid. As a result, the desorbed liquid can be easily reused in the separation and recovery of the laminate, and the environmental load can be further reduced.

The present invention is a laminate comprising at least a first substrate layer, an adhesive layer containing either polyethyleneimine or polybutadiene and having a mass per unit area of 5 to 100 mg/m ² , and a polyolefin resin layer in this order. The present invention relates to a method for separating and recovering a laminate, comprising a separation step of immersing the body in a desorption liquid to separate the polyolefin resin from the laminate, and a recovery step of recovering the separated polyolefin resin.
By combining the laminate comprising a polyolefin resin layer in contact with an adhesive layer containing either polyethyleneimine or polybutadiene and having a coating amount of 5 to 100 mg/m ² , and the separation step and recovery step, lamination is performed. Suspension of the desorbed liquid can be greatly reduced in the separation and recovery of bodies. In addition, when the recovered polyolefin resin is melt-recycled, it is possible to obtain a recycled resin in which deterioration of mechanical properties and coloration are suppressed.
Although the present invention will be described in detail below, these are examples of embodiments of the present invention, and the present invention is not limited to these contents as long as the gist thereof is not exceeded.

<Laminate>
The laminate in the present invention comprises at least a first substrate layer, an adhesive layer containing either polyethyleneimine or polybutadiene and having a mass per unit area of 5 to 100 mg/m ² , and a polyolefin resin layer in this order. It is characterized by

<First substrate layer>
The first substrate layer is not particularly limited, and includes film-like or sheet-like plastic substrates, metal foils, paper, etc., which are generally used for packaging packages of foods, etc., and is a laminate in which these are laminated. There may be.
Examples of the plastic substrate include films of thermoplastic resins and thermosetting resins, preferably films of thermoplastic resins. Examples of thermoplastic resins include polyolefin resins, polyester resins, polyamide resins, polystyrene resins, vinyl chloride resins, vinyl acetate resins, ABS resins, acrylic resins, acetal resins, polycarbonate resins, and cellulose plastics.

Specific examples of plastic substrates include polyolefin resin films such as polyethylene (PE) and biaxially oriented polypropylene (OPP); polyester resin film; polystyrene resin film; polyamide resin film such as nylon 6, poly-p-xylylene adipamide (MXD6 nylon); polycarbonate resin film; polyacrylonitrile resin film; polyimide resin film; bodies (eg, nylon 6/MXD6/nylon 6, nylon 6/ethylene-vinyl alcohol copolymer/nylon 6) and mixtures; Among them, those having mechanical strength and dimensional stability are preferable.
The thickness of the plastic substrate is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, still more preferably 10 μm to 50 μm.

The plastic substrate may have a vapor deposited layer of metal or metal oxide, or a barrier layer composed of an organic layer such as polyvinyl alcohol. are mentioned.
Examples of commercial products of plastic substrates having such a barrier layer include "GL FILM" (manufactured by Toppan Printing Co., Ltd.) and IB-FILM ( manufactured by Dai Nippon Printing Co., Ltd.).
Examples of metal foil include aluminum foil. The aluminum foil preferably has a thickness in the range of 3 to 50 μm from an economical point of view.
In addition, since aluminum and alumina are soluble in alkaline water, when the separation step described later is performed using an alkaline aqueous solution as a desorption liquid, the vapor deposition layer or aluminum foil made of aluminum or alumina will be removed from the first base material. It can be detached from the layer.

In the present invention, as described above, a polyolefin resin film such as polyethylene (PE) or biaxially oriented polypropylene (OPP) can be used as the first substrate layer. By using a polyolefin resin as the first substrate layer and combining it with a technology for detaching the printed layer, which will be described later, the polyolefin resin film, which is the first substrate layer, can be separated and recovered at the same time as the printed layer. can be recovered as a transparent polyolefin resin from which is desorbed, and the total amount of polyolefin resin recovered from the laminate can be increased.

[Printing layer/primer layer]
The first base material layer may further have a printed layer. The printed layer is a layer that forms an arbitrary printed pattern for the purpose of decoration, imparting aesthetics, content, expiration date, manufacturer's or seller's indication, etc., and includes a solid printed layer. The printed layer may be arranged in direct contact with the first base material, or may be arranged on the first base material layer via a primer layer.
The primer layer and the print layer are described below.

[Primer layer]
When the first substrate layer has a printed layer, a known primer layer may be arranged between the first substrate layer and the printed layer. The primer layer may be detachable from the first base layer together with the printed layer by immersion in a detachment solution to be described later. By providing such a primer layer, the printed layer can be easily separated from the first base material layer in the separation step. Thereby, when the first substrate layer is a polyolefin resin film, the total amount of polyolefin resin recovered from the laminate can be increased.
The primer layer preferably contains a water-soluble resin or a compound having an acidic group (excluding the water-soluble resin).

(Water-soluble resin)
As the water-soluble resin, any resin may be used as long as it can be swelled or dissolved in water and detached from the first base material layer. The water may be heated to a temperature of about 25-100°C. Thereby, the primer layer can be removed with water (including warm water).
Such resins can be selected from known resins as long as they do not impair water solubility. polyallylamine resins, water-soluble phenol resins, water-soluble epoxy resins, water-soluble phenoxy resins, water-soluble urea resins, water-soluble melamine resins, polyvinyl alcohol resins, and modified products of these resins. These can be used singly or in combination of two or more. Among them, polyvinyl alcohol (PVA) resin is preferably used from the viewpoint of availability and releasability.
When the water-soluble resin has film-forming properties, the water-soluble resin may be used as the binder resin constituting the primer layer.

Polyvinyl alcohol resins include, in addition to unmodified polyvinyl alcohol, modified polyvinyl alcohol obtained by copolymerizing various monomers during the production of vinyl ester resins and saponifying them, and various types of polyvinyl alcohol obtained by post-modification of unmodified polyvinyl alcohol. Various post-modified polyvinyl alcohols into which functional groups have been introduced may be used. Also, modified polyvinyl alcohol may be post-modified. These modification|denaturation can be performed in the range which does not impair the water-solubility of polyvinyl alcohol resin.
These resins may be used individually by 1 type, and may use 2 or more types together.

Preferable polyvinyl alcohol resins include resins containing structural units having primary hydroxyl groups in side chains and ethylene-modified polyvinyl alcohol resins. Among them, a polyvinyl alcohol resin containing a structural unit having a primary hydroxyl group in a side chain is preferable because of its excellent melt moldability and excellent water solubility. The number of primary hydroxyl groups in these structural units is generally 1-5, preferably 1-2, more preferably 1. Moreover, it is preferable to have a secondary hydroxyl group in addition to the primary hydroxyl group.

The degree of saponification (measured according to JIS K 6726) of the polyvinyl alcohol resin used in the present invention is usually 60 to 100 mol%. In addition, the preferred range of saponification degree varies depending on the modified species. 0.5%. The saponification degree of the side chain 1,2-diol structural unit-containing modified polyvinyl alcohol resin is usually 60 to 99.9 mol%, preferably 65 to 99.8 mol%, more preferably 70 to 99.5 mol%. be. If the degree of saponification is too low, the water solubility tends to decrease. The saponification degree of the ethylene-modified polyvinyl alcohol resin modified with a small amount of ethylene is usually 60 mol % or more, preferably 70 to 99.5 mol %, particularly preferably 75 to 99.0 mol %.
When the degree of saponification is within the above range, the water solubility is excellent and the releasability is improved, which is preferable. Moreover, it is preferable because it is excellent in coatability when forming a primer layer.

The average degree of polymerization of the polyvinyl alcohol resin (measured according to JIS K 6726) is generally 100-3000, preferably 150-2000, more preferably 180-1000, particularly preferably 200-800. Commercially available products include, for example, the JF series manufactured by Nippon Acetate & Poval Co., Ltd., the Poval series manufactured by Kuraray Co., Ltd., and the Exeval series.

(Compound having an acidic group)
As the compound having an acidic group, a resin having an acidic group or a low-molecular-weight compound having an acidic group may be used. Thereby, the primer layer can be removed with a removing liquid (alkaline aqueous solution).
Examples of resins having an acidic group include cellulose resins, urethane resins, polyamide resins, vinyl chloride/vinyl acetate copolymers, ketone resins, polyester resins, and (meth)acrylic resins. Examples of the acidic group include a carboxy group, a phosphoric acid group, a sulfo group, a sulfino group, etc., or an ester or salt thereof.
As the resin having an acidic group, a rosin-modified resin having an acid value such as maleated rosin and fumarated rosin can be used.
In addition, as the resin having an acidic group, a polymerizable monomer having a carboxy group such as itaconic acid, maleic acid, fumaric acid, and cinnamic acid; a polymerizable monomer that is an acid anhydride such as itaconic anhydride and maleic anhydride; Polymerizable monomers having a sulfonic acid group such as styrene; Polymerizable monomers having a sulfonamide group such as vinylbenzenesulfonamide; Polymerizable monomers having an acidic group such as styrene-(meth)acrylic Resins, radical copolymers such as styrene-(anhydride) maleic acid resins and terpene-(anhydride) maleic acid resins, and acid-modified polyolefin resins can be used.
These may be used individually by 1 type, and may use 2 or more types together.

A low-molecular-weight compound having an acidic group refers to a compound having no molecular weight distribution and having a molecular weight of 1,000 or less. Examples of such compounds include saturated fatty acids such as lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid; hydroxy acids such as lactic acid, malic acid, and citric acid; aromatic carboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, and cinnamic acid; oxalic acid, Dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, and maleic acid; tricarboxylic acids such as aconitic acid; oxocarboxylic acids such as pyruvic acid and oxaloacetic acid; carboxylic acid derivatives such as amino acids and nitrocarboxylic acids and acid anhydrides such as trimellitic anhydride and pyromellitic anhydride.
A low-molecular-weight compound having an acidic group may form a primer layer in combination with a resin having an acidic group or a known binder resin.

[Print layer]
The method for forming the printed layer is not limited, and it can be formed using a known method.
The printing layer contains known binder resins and colorants used in printing inks and paints.
Examples of binder resins include fibrous materials such as nitrocellulose, cellulose acetate and propionate, chlorinated polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, acrylic, urethane resin, acrylic urethane, and polyamide. , polybutyral-based, cyclized rubber-based, and chlorinated rubber-based resins. These resins may be used individually by 1 type, and may use 2 or more types together.
Among them, when the first base material is a plastic base material, urethane resin-based, polyester-based, and chlorinated polypropylene-based adhesives are preferably used because of their excellent adhesiveness to the plastic base material.

The coloring agent is not particularly limited, and inorganic pigments, organic pigments, dyes, metal powders that give metallic luster, near-infrared absorbing materials, and ultraviolet absorbing materials may be used. Examples of inorganic pigments include colored pigments such as titanium oxide, red iron oxide, Prussian blue, ultramarine blue, carbon black and graphite; and extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide and talc. Examples of organic pigments include those described by the generic names of the Color Index, and for example, soluble azo pigments, insoluble azo pigments, azo chelate pigments, condensed azo pigments, copper phthalocyanine pigments, condensed polycyclic pigments, etc. can be suitably used. can.
The printed layer may also contain a pigment derivative or a resin-type dispersant as a dispersant for the colorant.

The printed layer may be releasable from the desorbing liquid, and may contain, for example, a water-soluble resin or a compound containing an acidic group (excluding the water-soluble resin). For the water-soluble resin and the compound having an acidic group, the descriptions of (water-soluble resin) and (compound having an acidic group) in the section [Primer layer] can be used.
By providing such a printed layer, the printed layer can be easily separated from the first base material layer in the separation step. Thereby, when the first substrate layer is a polyolefin resin film, the total amount of polyolefin resin recovered from the laminate can be increased.

The printing ink forming the printing layer in the present invention may contain a curing agent within a range that does not impair the effects of the present invention. By including the curing agent, it reacts with the binder resin in the printing ink and the hydroxyl groups and carboxyl groups on the surface of the base material, thereby improving the adhesive strength and content resistance of the laminate.
The amount of the curing agent contained in the printing ink is preferably 0% by mass or more and 5% by mass or less based on the solid content of the printing ink. When the amount of the curing agent is 5% by mass or less, the curing agent contained in the printed layer can be prevented from excessively migrating to the adhesive layer formed on the printed layer, and the separability is not impaired.
Examples of the curing agent that the printing ink may contain include isocyanate curing agents and silane coupling agents.

The thickness of the printed layer is preferably 0.1 μm to 100 μm, more preferably 0.1 μm to 10 μm, still more preferably 1 μm to 5 μm.

<Adhesive layer>
The adhesive layer in the present invention is a layer arranged between the first substrate layer and the polyolefin resin layer, more specifically, in contact with the first substrate layer or the printed layer included in the first substrate layer. A layer characterized by containing either polyethyleneimine or polybutadiene and having a mass per unit area of 5 to 100 mg/m ² .
The adhesive layer can exhibit lamination strength between the first substrate layer and the polyolefin resin layer described below with a small coating amount of 5 to 100 mg/m ² . In addition, when the adhesive layer is immersed in a desorbing liquid, the polyolefin resin can be separated by dissolving and peeling. can be reduced.

[Polyethyleneimine]
The polyethyleneimine used in the present invention is a water-soluble polymer obtained by polymerizing ethyleneimine, and represents one that can be dissolved in water or alcohol. The polyethyleneimine is preferably a branched polyethyleneimine having a primary, secondary, or tertiary amino group in the molecule and a branched structure in the molecule, and known ones can be used.
Commercial products of such polyethyleneimine include, for example, Epomin SP-003, Epomin SP-006, Epomin SP-012, Epomin SP-018, Epomin SP-200, Epomin HM-2000 and Epomin P manufactured by Nippon Shokubai Co., Ltd. -1000, Epomin P-3000; LOXANOL MI6721, LOXANOL MI6730, LOXANOL MI6735 manufactured by BASF; These polyethyleneimine may be used individually by 1 type, and may use 2 or more types together.
From the viewpoint of laminate strength, the number average molecular weight of polyethyleneimine is preferably 10,000 or more and 180,000 or less, more preferably 30,000 or more and 150,000 or less, still more preferably 50,000 or more and 100,000. It is below.

[Polybutadiene]
The polybutadiene used in the present invention may be a polymer having butadiene as a constituent unit, and commercially available products such as Seikadyne (trade name) from Dainichiseika Kogyo Co., Ltd. and Chitabond (trade name) from Nippon Soda Co., Ltd. are available. The butadiene is preferably derived from 1,2-polybutadiene, and among them, modified 1,2-polybutadiene such as "Titabond T180E" manufactured by Nippon Soda Co., Ltd. is preferably used from the viewpoint of releasability. This is presumably because "Titabond T180E" can form an emulsion and has a hydrophilic structure. One type of polybutadiene may be used alone, or two or more types may be used in combination.

The adhesive layer in the present invention is formed by using a composition (adhesive) containing either polyethyleneimine or polybutadiene and a medium containing one or more of water and an alcoholic organic solvent, for example, by gravure coater method, roll It can be provided by a known method such as a coater method. After applying the adhesive, a drying step may be provided as necessary.
It is important that the mass per unit area of the adhesive layer is 5 to 100 mg/m ² from the viewpoint of suppressing contamination of the desorbing liquid. The coating amount of the adhesive layer of less than 5 mg/m ² is insufficient, and it is difficult to maintain the adhesive strength required for the laminate. On the other hand, if it exceeds 100 mg/m ² , the amount dissolved or dispersed in the stripping liquid increases, causing contamination of the stripping liquid.
The mass per unit area of the adhesive layer is preferably 10 mg/m 2 or more from the viewpoint of adhesive strength, ^and preferably 50 mg/m ² or less, more preferably 30 mg/m 2 or less from the viewpoint of suppressing contamination of the desorbing liquid. ^m2 or less.
The mass of the adhesive layer can be controlled by adjusting the plate depth and roll transfer amount when applying the adhesive, and by adjusting the solid content of the adhesive.

The adhesive that forms the adhesive layer in the present invention may contain a curing agent within a range that does not impair the effects of the present invention. By including the curing agent, it reacts with the binder resin in the adhesive, the printed layer surface, and the hydroxyl groups and carboxyl groups on the polyolefin resin surface, thereby improving the adhesive strength and content resistance of the laminate. The amount of the curing agent contained in the adhesive is preferably 0% by mass or more and 5% by mass or less based on the solid mass of the adhesive. When the amount of the curing agent is 5% by mass or less, the dissolution rate and swelling rate of the adhesive layer in the removing liquid do not decrease, and the separability is not impaired.
The curing agent that the adhesive may contain includes, for example, a water-dispersible isocyanate curing agent and a silane coupling agent.

[Other ingredients]
The adhesive layer may contain other components as long as the effects of the present invention are not impaired. Examples of such components include other resins for improving film-forming properties and anti-blocking properties, leveling agents for improving wettability, and antifoaming agents for suppressing foaming during coating. be done.
Polyvinyl acetate is preferably used as the other resin, and commercially available products include Gohsenyl series manufactured by Mitsubishi Chemical Corporation, Pegal series manufactured by Koatsu Gas Kogyo Co., Ltd., and VINNAPAS series manufactured by WACKER POLYMER.
Commercially available leveling agents and antifoaming agents include, for example, Surfynol series manufactured by Nisshin Chemical Co., Ltd., TEGOGLIDE series manufactured by TEGO, and TEGOFOAMEX series.

The adhesive layer contains either polyethyleneimine or polybutadiene, and preferably contains 50% by mass or more of polyethyleneimine and polybutadiene in total based on the mass of the adhesive layer. The total content of polyethyleneimine and polybutadiene in the adhesive layer is preferably 60% by mass or more, more preferably 75% by mass or more, from the viewpoint of achieving both maintenance of adhesive strength and separability.

<Polyolefin resin layer>
The polyolefin resin layer in the present invention may be a layer containing polyolefin resin as a main component. Since polyolefin resin is excellent in stability, it is excellent in that it does not contaminate the desorbed liquid. Further, the main component means 90% by mass or more, preferably 95% by mass or more, based on the mass of the polyolefin resin layer.

The polyolefin resin layer is preferably formed by an extrusion lamination method from the viewpoint of adhesive strength. Lamination using an extrusion lamination method is preferable because good adhesive strength can be exhibited even when the amount of the adhesive layer applied is as small as 5 to 100 mg/m ² . As the extrusion lamination method, for example, a molten polyolefin resin is extruded by an extruder, extruded into a film form by a jig called a T-die, and then placed on the first substrate by a press roll and a cooling roll. A method of laminating a polyolefin resin layer by pressure-bonding with an adhesive layer formed on the substrate may be mentioned.

The polyolefin resin used for extrusion lamination can be appropriately selected from known polyethylene resins, polypropylene resins, and the like. Low-density polyethylene or polypropylene having a density of 0.85 to 0.93 g/cm ³ and a melt flow rate (MFR) of 1 to 30 g/10 min is preferably used from the viewpoint of workability.
The melting temperature of the polyolefin resin can be adjusted by the melt flow rate of the contained resin, etc. From the viewpoint of adhesive strength, it is preferably 270° C. or higher, more preferably 290° C. or higher immediately below the T-die extrusion.
Examples of commercial products of such polyolefin resins include Novatec LD series (manufactured by Japan Polyethylene Corporation), Pedrocene series (manufactured by Tosoh Corporation), and Novatec PP series (manufactured by Japan Polypropylene Corporation). These polyolefin resins may be used alone or in combination of two or more.

The thickness of the polyolefin resin layer can be adjusted by changing the extrusion speed depending on the application and purpose. 30 μm.

<Production of laminate>
The laminate in the present invention comprises at least a first substrate layer, an adhesive layer containing either polyethyleneimine or polybutadiene and having a mass per unit area of 5 to 100 mg/m ² , and a polyolefin resin layer. For example, a method of laminating a molten polyolefin resin on an adhesive layer of a first base material layer comprising an adhesive layer containing either polyethyleneimine or polybutadiene by extrusion lamination. be done. The adhesive layer can be formed, for example, by applying an adhesive containing polyethyleneimine and/or polybutadiene by a known method such as gravure coater method or roll coater method.

[Sealant base layer]
The laminate in the present invention may further have a sealant base layer. Examples of sealant base materials include polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), acid-modified polyethylene, polypropylene (PP), acid-modified polypropylene, copolymerization Examples include polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-(meth)acrylic acid copolymer, and ionomer.
The sealant base layer may be a polyolefin resin film such as polyethylene or polypropylene, as described above. When the sealant base material is a polyolefin resin film, the sealant base material can be collected together when the polyolefin resin is separated and collected, and the total amount of the polyolefin resin collected from the laminate can be increased, which is preferable.

The arrangement position and lamination method of the sealant base layer are not particularly limited. can be provided. As the adhesive used for dry lamination, a known adhesive can be used, and an adhesive having releasability that is detached with a detachment liquid may be used. The sealant base material can be separated and collected by using an adhesive having releasability.

Further, for example, the sealant base material layer can be provided on the surface opposite to the adhesive layer in contact with the polyolefin resin layer described above. In this case, the sealant base material layer can be laminated by extrusion laminating the adhesive layer surface of the first base material layer having the adhesive layer and the sealant base material via the melted polyolefin resin.

When the sealant base material is a polyolefin resin film and is arranged in contact with the polyolefin resin layer, the sealant base material layer and the polyolefin resin layer can be separated and collected together without separation. .

Also, for example, the sealant base layer may comprise a barrier layer comprising a deposited layer of metal or metal oxide. Examples of the deposited layer include deposited layers of aluminum, silica, alumina, and the like. Since the vapor-deposited layer dissolves in an alkaline aqueous solution, when the sealant base material is a polyolefin resin film, it can be collected together with the polyolefin resin.

Although the thickness of the sealant base layer is not particularly limited, it is preferably 10 to 200 μm, more preferably 15 to 150 μm, in consideration of workability to packaging materials, heat sealability, and the like. Further, the sealant base material may be provided with unevenness having a height difference of about several μm to impart slipperiness and tearability to the packaging material.

[Other layer]
The laminate in the present invention may further have known layers as long as the effects of the present invention are not impaired. Layers that may be included include, for example, an adhesive layer, a plastic substrate layer, metal foil, paper, an overcoat layer, and a heat seal layer. good too.

A specific configuration example of the laminate in the present invention will be given.
First substrate layer/adhesive layer/polyolefin resin layer First substrate layer/printing layer/adhesive layer/polyolefin resin layer/sealant substrate layer First substrate layer/primer layer/printing layer/adhesive layer/ Polyolefin resin layer/Sealant base layer First base layer/Printing layer/Adhesive layer/Polyolefin resin layer/Sealant base layer First base layer/Printing layer/Adhesive layer/Polyolefin resin layer/Deposited film layer/ Adhesive layer/polyolefin resin layer/sealant substrate layer Sealant substrate layer/polyolefin resin layer/adhesive layer/first substrate layer/printing layer/adhesive layer/polyolefin resin layer

<Laminate Separation and Collection Method>
The method for separating and recovering a laminate of the present invention comprises a separation step of immersing the above-described laminate in a desorption liquid to separate the polyolefin resin from the laminate, and a recovery step of recovering the separated polyolefin resin. is. In the present invention, when the separated and recovered polyolefin resin is reused as a recycled base material or a recycled base material, components other than the polyolefin resin contained in the recovered polyolefin resin (e.g., first base material, adhesive, printing component derived from ink, etc.) is preferably as small as possible.
Furthermore, when another layer included in the laminate is made of polyolefin, such as the first base material and the sealant base material provided in contact with the polyolefin resin layer, these resins are also recovered from the polyolefin resin. It is possible to recover the polyolefin resin at the same time, and the total amount of the recovered polyolefin resin can be increased, which is preferable.
The amount of polyolefin resin to be recovered (recovery rate) is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 80% by mass, based on the mass of all plastic substrates contained in the laminate. 90% by mass or more, particularly preferably 90% by mass or more.

[Separation process]
The desorbing liquid used in the separation step dissolves or swells the adhesive layer containing either polyethyleneimine or polybutadiene and having a mass per unit area of 5 to 100 mg/m ² to separate the polyolefin resin. Anything that can be done is good. By immersing the laminate in the detachment liquid, the adhesive layer dissolves or swells and is separated from the first substrate layer and the adhesive layer, so that the adhesive layer can be separated from the first substrate layer. .

(desorption liquid)
Examples of such a desorption liquid include water, an alkaline aqueous solution, an acidic aqueous solution, and a fluorinated solvent, and may contain a surfactant and/or an antifoaming agent.
The desorption liquid is preferably an aqueous solution containing water such as water, an alkaline aqueous solution, or an acidic aqueous solution, more preferably water or an alkaline aqueous solution, from the viewpoint of reducing the environmental load and maintaining the properties of the recovered polyolefin resin. More preferably, it contains a surfactant with an HLB value of 7 or more, and particularly preferably contains a surfactant with an HLB value of 7 or more and an antifoaming agent with an HLB value of 1 to 3. Further, the detached liquid may be heated, and the temperature is preferably 40° C. to 90° C. from the viewpoint of separability.
The HLB value is an index value relating to affinity for water and oil, and is divided equally between 0 for a substance having no hydrophilic group and 20 for a substance having only a hydrophilic group. The concept of HLB was proposed by William Griffin of the Atlas Powder Company in 1949, and several methods of determination by calculation have been proposed. In the present invention, the HLB value can be obtained from the following equation using the Griffin method. .
Formula: HLB = 20 × [(molecular weight of hydrophilic group contained in surfactant) / (molecular weight of surfactant)]
Hydrophilic groups contained in surfactants include, for example, hydroxyl groups and ethyleneoxy groups.

《Alkaline aqueous solution》
The alkaline aqueous solution is preferably an aqueous solution containing a basic compound and having a pH of 12 or higher. Basic compounds are not particularly limited, and examples include sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), ammonia, barium hydroxide (Ba(OH) ₂ ), carbonate Sodium (Na ₂ CO ₃ ) is preferably used, but is not limited thereto. More preferably, it is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide.
The alkaline aqueous solution preferably contains 0.5 to 20% by mass, more preferably 1 to 15% by mass, and still more preferably 3 to 15% by mass of a basic compound in the aqueous solution. When the concentration is within the above range, the adhesive layer is efficiently dissolved or swelled, and separation of the polyolefin resin is excellent.

《Surfactant》
Surfactants with an HLB value of 7 or more play a role in improving the separability of the adhesive layer and the like. This is probably because the release liquid contains a surfactant with an HLB value of 7 or more, which facilitates the penetration of the release liquid into the adhesive layer and promotes the separation.
The content of the surfactant in the detached liquid is preferably in the range of 0.001 to 10% by mass, more preferably in the range of 0.03 to 3% by mass, based on the mass of the detached liquid. .

Types of surfactants having an HLB value of 7 or more include, for example, nonionic, anionic, cationic, and amphoteric surfactants, and suitable types and blending amounts can be appropriately selected according to required properties. From the viewpoint of releasability and foamability, it is preferably at least one selected from the group consisting of anionic surfactants and nonionic surfactants. Further, the surfactant preferably has a structure to which an alkylene oxide (hereinafter also referred to as AO) is added, because it has good releasability.

《Antifoaming agent》
In the present invention, the antifoaming agent has an HLB value in the range of 1 to 3, and when used in combination with a surfactant having an HLB value of 7 or more, exhibits good antifoaming properties, Foaming caused by the surfactant can be suppressed. As a result, it is possible to improve the stirring speed by suppressing bubbles during detachment, suppress separation hindrance due to bubbles during specific gravity separation described later, and facilitate recovery of floating polyolefin resin.
Examples of the antifoaming agent include silicone compounds and non-silicone compounds. An antifoaming agent may be used individually by 1 type, and may use 2 or more types together.
The content of the antifoaming agent in the stripped liquid is preferably in the range of 0.0001 to 3% by mass, more preferably in the range of 0.01 to 1% by mass, based on the mass of the stripped liquid. .

(Shredding process)
The release liquid permeates from the edge portion of the laminate, contacts the adhesive layer, and dissolves or swells the adhesive layer, thereby separating the polyolefin resin layer from the first substrate layer and other layers in contact with the polyolefin resin layer. detach from Therefore, in order to proceed with the separation step efficiently, it is preferable to have a shredding step of cutting or crushing the laminate and exposing the adhesive layer on the cross section before the separation step. By providing the shredding step, the polyolefin resin can be separated from the first substrate and other layers with which the polyolefin resin layer is in contact in a shorter period of time.
The method for shredding or crushing the laminate is not particularly limited, and examples thereof include methods using a jaw crusher, impact crusher, cutter mill, stamp mill, ring mill, roller mill, jet mill, and hammer mill.

The immersion time in the desorbing solution is preferably 1 minute to 24 hours, more preferably 1 minute to 12 hours, still more preferably 1 minute to 6 hours. The amount of the desorbing liquid used is preferably 10 to 100 times, more preferably 25 to 100 times the mass of the laminate, from the viewpoint of the quality of the recycled plastic and processing efficiency. In order to improve separation efficiency, it is preferable to stir or circulate the desorbed liquid. The rotation speed for stirring is preferably 80-3000 rpm, more preferably 200-2000 rpm.

[Recovery process]
The method for recovering the polyolefin resin is not particularly limited. For example, the polyolefin resin can be selectively recovered using a gravity separation method.
In the gravity separation method, the polyolefin resin separated in the separation step can be separated from the printed layer and the first substrate by utilizing the difference in specific gravity. Moreover, when the first base material and the sealant base material contained in the laminate are made of polyolefin and the printed layer and the like can be removed in the separation step, they can be recovered together with the polyolefin resin layer.

(Removal process/washing process)
The separation and recovery method of the present invention may have a removal step of removing the base material to which the printed layer and the adhesive layer are attached after the recovery step. The removal method is not particularly limited, and examples thereof include a method using an optical sensor such as an infrared sensor or a color sorting sensor.
In the separation and recovery method of the present invention, after the recovery step, a cleaning step may be provided in which the recovered polyolefin resin is washed with water to wash away the attached desorbed liquid and impurities, and a drying step may be provided as necessary. good too.
The order of the removing step and the washing step is not limited, and either may be performed first.

<Reuse of polyolefin resin>
The polyolefin resin recovered by the separation and recovery method of the present invention can be subjected to a pelletizing step and reused as a recycled resin.
The pelletizing step is a step of adding various additives as necessary, mixing them with a Henschel mixer, a tumbler, a disper, or the like, and then melting and kneading them.
Examples of melt-kneading equipment include kneaders, roll mills, super mixers, Henschel mixers, Shugi mixers, vertical granulators, high-speed mixers, furmatrices, ball mills, steel mills, sand mills, vibration mills, attritors, and Banbury mixers. batch kneaders, twin-screw extruders, single-screw extruders, and rotor-type twin-screw kneaders.
The shape after pelletizing is not particularly limited, and may be any shape such as pellets, powders, granules, and beads.

The recycled resin may further contain a masterbatch. The masterbatch is not particularly limited as long as it is compatible with the recycled resin, and generally a mixture of a thermoplastic resin such as polyethylene resin or polypropylene resin and a colorant kneaded can be used. The thermoplastic resin contained in the masterbatch may be used alone or in combination of two or more.

The coloring agent is not particularly limited as long as it is commonly used in masterbatches, and examples thereof include inorganic pigments such as titanium oxide, chrome titanium aero, red iron oxide, ultramarine blue, and carbon black; azo pigments; Organic pigments such as quinacridone-based pigments, perylene-based pigments, diketopyrrolopyrrole-based pigments, and phthalocyanine-based pigments are included.

The masterbatch contains alkali metal, alkaline earth metal, or zinc metallic soap, hydrotalcite, nonionic surfactant, cationic surfactant, anionic surfactant, amphoteric surfactant, as long as it does not impair the effects of the present invention. Surfactants, antistatic agents, flame retardants such as halogen-based, phosphorus-based or metal oxides, lubricants such as ethylenebisalkylamide, antioxidants, ultraviolet absorbers and fillers may be contained.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these Examples. In addition, "parts" and "%" in the present invention represent "mass parts" and "mass%" unless otherwise specified.

Methods for measuring the molecular weight, molecular weight distribution, acid value and hydroxyl value of the synthesized polyester polyols P1 to P2 and urethane varnishes B1 and B3 are shown below.
<Molecular weight and molecular weight distribution>
Weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) were measured by GPC (gel permeation chromatography), and were obtained as converted molecular weights using polystyrene as a standard substance. Measurement conditions are shown below.
GPC device: Showa Denko Shodex GPC-104
Column: The following columns were connected in series and used.
Showa Denko Shodex LF-404 2 Showa Denko Shodex LF-G
Detector: RI (differential refractometer)
Measurement conditions: Column temperature 40°C
Eluent: Tetrahydrofuran Flow rate: 0.3 mL/min

<Acid value, hydroxyl value>
The acid value and hydroxyl value were measured according to JIS K 0070 (1992).

<Manufacture of adhesive>
(Manufacture of adhesive T1)
0.70 parts of Epomin P-1000 (polyethyleneimine solution manufactured by Nippon Shokubai Co., Ltd.), 29.79 parts of water and 69.51 parts of ethanol were mixed to obtain an adhesive T1 having a non-volatile content of 0.2%.

(Manufacture of adhesives T2 to T14)
Adhesives T2 to T14 were obtained in the same manner as for adhesive T1, except that the raw materials and formulations shown in Table 1 were used.

Abbreviations in Table 1 are shown below.
Epomin P-1000 (polyethyleneimine solution manufactured by Nippon Shokubai Co., Ltd.): number average molecular weight 70,000, non-volatile content 30% by mass
Epomin SP-018 (polyethyleneimine manufactured by Nippon Shokubai Co., Ltd.): number average molecular weight 1,800
Epomin SP-200 (polyethyleneimine manufactured by Nippon Shokubai Co., Ltd.): number average molecular weight 10,000
Titabond T-180E (emulsion type polybutadiene manufactured by Nippon Soda Co., Ltd.): non-volatile content 10% by mass
Gohsenyl M50-Z8 (polyvinyl acetate manufactured by Mitsubishi Chemical Corporation) non-volatile content 50% by mass
Pegal 150 (polyvinyl acetate manufactured by Koatsu Gas Kogyo Co., Ltd.) non-volatile content 42% by mass
KBM-403 (3-glycidoxypropyltrimethoxysilane manufactured by Shin-Etsu Chemical Co., Ltd.)

(Production of adhesives T15 to T17)
A polyurethane-based adhesive described in JP-A-2021-088184 was used as adhesives T15 to T17. Specifically, 90 parts of a polyester polyol (P1) solution, 10 parts of a polyester polyol (P2) solution, and 8 parts of a polyisocyanate (C1) solution shown below are mixed, and ethyl acetate is added to obtain a nonvolatile content of 30%. An adhesive solution was prepared.
The adhesive solution was further diluted with ethyl acetate to a non-volatile content of 2% to obtain an adhesive T15. Adhesive T16 was similarly diluted to a nonvolatile content of 6%, and adhesive T17 was obtained by diluting to a nonvolatile content of 18%.

<<Synthesis of polyester polyol P1>>
124 parts of ethylene glycol, 212 parts of neopentyl glycol, 368 parts of 1,6-hexanediol, 645 parts of isophthalic acid and adipine were placed in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank and nitrogen gas inlet tube. 36 parts of acid and 265 parts of sebacic acid were charged, and the temperature was raised to 250° C. while stirring under a nitrogen stream to carry out an esterification reaction. After a predetermined amount of water was distilled and the reaction was continued until the acid value became 5 or less, the pressure was gradually reduced and deglycol reaction was carried out at 1 mmHg or less for 5 hours to obtain a polyester polyol. After that, 35 parts of isophorone diisocyanate was gradually added and reacted at 150° C. for about 2 hours to obtain a polyester polyurethane polyol. 12.0 parts of ethylene glycol bis-anhydrotrimellitate was added to 100 parts of this polyester polyurethane polyol, reacted at 180° C. for about 2 hours, and then diluted with ethyl acetate until the non-volatile content reached 50%. A solution of partially acid-modified polyester polyol P1 having a molecular weight of 9,000 and an acid value of 30.3 mgKOH/g was obtained.

<<Synthesis of polyester polyol P2>>
58 parts of ethylene glycol, 412 parts of diethylene glycol, 343 parts of neopentyl glycol, 517 parts of isophthalic acid, and 393 parts of adipic acid are charged into a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank and nitrogen gas inlet tube. , the temperature was raised to 250° C. with stirring under a nitrogen stream to carry out an esterification reaction. After a predetermined amount of water was distilled and the reaction was continued until the acid value became 5 or less, the pressure was gradually reduced and deglycol reaction was carried out at 1 mmHg or less for 5 hours to obtain a polyester polyol. 4.0 parts of trimellitic anhydride was added to 100 parts of this polyester polyol, reacted at 180° C. for about 2 hours, and then diluted with ethyl acetate until the non-volatile content reached 50%. A solution of partially acid-modified polyester polyol P2 having an acid value of 23.5 mgKOH/g was obtained.

<<Adjustment of Polyisocyanate C1>>
Coronate 2785 (a biuret-type polyisocyanate derived from hexamethylene diisocyanate, manufactured by Tosoh Corporation) was diluted with ethyl acetate to adjust the non-volatile content to 50% and the NCO% to 9.6% to obtain a solution of polyisocyanate C1. rice field.

<Production of printing ink>
(Production of printing ink I1)
Polyurethane varnish B1 (KL-593 manufactured by Arakawa Chemical Co., Ltd.: polyester-polyether combination polyurethane varnish solid content concentration 30%) 30 parts, vinyl chloride-vinyl acetate copolymer resin varnish (Solbin TAO manufactured by Nissin Chemical Co., Ltd.: solid content concentration 30 % ethyl acetate solution), 10 parts of indigo pigment (Lionol Blue FG7330 manufactured by Toyocolor Co., Ltd.), and 20 parts of a mixed solvent of normal propyl acetate / isopropyl alcohol = 70/30 (mass ratio) are stirred and mixed, Dispersion treatment was performed for 20 minutes using a sand mill. Thereafter, 30 parts of the same mixed solvent was stirred and mixed to obtain printing ink I1.

(Production of printing ink I2)
A printing ink was obtained in the same manner as for printing ink I1, except that polyurethane varnish B1 was changed to polyester varnish B2 (Vylon 200 manufactured by Toyobo Co., Ltd.: polyester varnish solid content concentration 30% ethyl acetate solution). To 100 parts of this printing ink, 3 parts of a hexamethylene diisocyanate bifunctional prepolymer (Asahi Kasei Duranate D101, a solution diluted with ethyl acetate to a solid concentration of 50%) was added to obtain printing ink I2.

(Production of printing ink I3)
To 100 parts of printing ink I1, 3 parts of hexamethylene diisocyanate bifunctional prepolymer (Asahi Kasei Duranate D101, a solution diluted with ethyl acetate to a solid concentration of 50%) was added to obtain printing ink I3.

<Manufacture of primer composition>
(Production of Polyurethane Resin B3)
While introducing nitrogen gas in a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet tube, a stirrer, and a thermometer, PPA (consisting of a polycondensate of propylene glycol and adipic acid, having a number average molecular weight of 2, 000 polyester polyol), 13.6 parts of PPG (polyether polyol consisting of polypropylene glycol and having a number average molecular weight of 2,000), 28.3 parts of 2,2-dimethylolpropanoic acid, and 106 parts of isophorone diisocyanate. 7 parts and 200 parts of normal propyl acetate were charged and reacted at 90° C. for 5 hours to obtain a urethane prepolymer solution having terminal isocyanate groups.
Next, a mixture of 16.7 parts of 2-(2-aminoethylamino)ethanol and 350 parts of isopropyl alcohol was added dropwise at room temperature over 60 minutes, followed by reaction at 70° C. for 3 hours to obtain a polyurethane resin solution. got
150 parts of normal propyl acetate was added to the obtained polyurethane resin solution to adjust the solid content, and the solid content concentration was 30%, the weight average molecular weight was 30,000, Mw/Mn = 3.0, and the acid value was 38.3 mgKOH/g. , a solution of polyurethane resin B3 having a hydroxyl value of 30.5 mg KOH/g was obtained.

(Production of Primer Composition S1)
87 parts of polyurethane resin B3 solution, 5 parts of ethyl acetate, 5 parts of isopropyl alcohol, and 3 parts of silica particles (P-73 manufactured by Mizusawa Chemical Co., Ltd.: hydrophilic silica particles with an average particle diameter of 3.8 μm) are stirred using a disper. After mixing, primer composition S1 was obtained.

(Production of Primer Composition S2)
5 parts of polyvinyl alcohol resin (JF-03 manufactured by Nippon Acetate & Poval Co., Ltd.) and 95 parts of water were stirred and mixed using a disper at 95° C. to obtain primer composition S2.

(Production of Primer Composition S3)
30 parts of polyurethane varnish B1, 10 parts of vinyl chloride-vinyl acetate copolymer resin varnish, 2 parts of pyromellitic anhydride, and 58 parts of a mixed solvent of normal propyl acetate/isopropyl alcohol = 70/30 (mass ratio) were dispersed. were mixed with stirring to obtain a primer composition S3.

<Production of laminate>
(Laminate L1)
Adhesive T1 is applied to the treated surface of OPP (corona-treated biaxially oriented polypropylene film, thickness 20 μm) using a gravure coater equipped with a gravure plate with a plate depth of 15 μm, and dried at 80° C. to form an adhesive layer. formed. On the adhesive layer, LDPE (low-density polyethylene manufactured by Japan Polyethylene Co., Ltd.: Novatec LLC520) is extrusion-laminated at a melting temperature of 310 ° C. to form a laminate by pressure bonding with CPP (corona-treated unstretched polypropylene film, thickness 30 μm). L1 was obtained. The mass (application amount) per unit area of the adhesive layer was 10 mg/m ² , and the thickness of the LDPE layer was 15 µm.

(Laminate L2)
A laminate L2 was obtained in the same manner as for the laminate L1, except that the content shown in Table 2 was changed.

(Laminate L3)
The diluted printing ink I1 was printed on the OPP-treated surface using a gravure printing machine equipped with a gravure plate having a plate depth of 30 μm, and dried at 50° C. to form a printed layer. Thereafter, the adhesive T1 was applied onto the printed layer using a gravure coater equipped with a gravure plate having a plate depth of 15 μm, and dried at 80° C. to form an adhesive layer. LDPE was extrusion-laminated on the adhesive layer at a melting temperature of 310° C., and pressed against CPP to obtain a laminate L3. The coating amount of the adhesive layer was 10 mg/m ² and the thickness of the LDPE layer was 15 μm.

(Laminates L4 to L15, L17 to L20, L24 to L29)
Laminated bodies L4 to L15, L17 to L20, and L24 to L29 were obtained in the same manner as for laminated body L3, except that the contents were changed as shown in Table 2. The laminates L19, L27, and L29 were produced without crimping the sealant base material.

(Laminate L16)
The diluted printing ink I1 was printed on the OPP-treated surface using a gravure printing machine equipped with a gravure plate having a plate depth of 30 μm, and dried at 50° C. to form a printed layer. Adhesive T1 was applied onto the printed layer using a gravure coater equipped with a gravure plate having a plate depth of 15 μm, and dried at 80° C. to form an adhesive layer. On the adhesive layer, LDPE was extrusion-laminated at a melting temperature of 310° C., and laminated by being pressure-bonded to the vapor-deposited surface of VMPET.
Next, the adhesive T1 was applied to the PET surface of VMPET using a gravure coater equipped with a gravure plate having a plate depth of 15 μm, and dried at 80° C. to form an adhesive layer. On the adhesive layer, LDPE was extrusion-laminated at 310° C. and pressed against CPP to obtain laminate L16. The coating amount of each adhesive layer was 10 mg/m ² , and the thickness of each LDPE layer was 15 μm.

(Laminate L21)
Primer composition S1 diluted with ethyl acetate to a non-volatile content of 1% was printed on the OPP-treated surface with a gravure plate having a plate depth of 15 μm and dried at 50° C. to form a primer layer. Printing ink I1 was printed on the primer layer using a gravure printing machine equipped with a gravure plate having a plate depth of 30 μm, and dried at 50° C. to form a printing layer. Adhesive T1 was applied onto the printed layer using a gravure coater equipped with a gravure plate having a plate depth of 15 μm, and dried at 80° C. to form an adhesive layer.
After that, LDPE was extrusion-laminated on the adhesive layer at a melting temperature of 310° C. and pressed against CPP to obtain a laminate L21. The coating amount of each adhesive layer was 10 mg/m ² , and the thickness of each LDPE layer was 15 μm.

(Laminates L22, L23)
Laminated bodies L22 and L23 were obtained in the same manner as for laminated body L21, except that the contents were changed as shown in Table 2. Water was used to dilute the primer S2 in the laminate L22.

(Laminates LL1, 8, 10)
Comparative laminates LL1, 8 and 10 were obtained in the same manner as laminate L1 except that the materials and melting temperatures were changed to those shown in Table 3 and the adhesive layer was not used. Note that the laminate LL10 was produced without crimping the sealant base material.

(Laminates LL2, 9, 11, 12)
The materials and melting temperatures shown in Table 3 were changed, and instead of using no adhesive layer, the printed layer was subjected to corona discharge treatment immediately before extrusion lamination. Laminates LL2, 9, 11 and 12 for Note that the laminate LL11 was produced without crimping the sealant base material.

(Laminates LL3-7)
Comparative laminates LL3 to LL7 were obtained in the same manner as laminate L1, except that the materials and melting temperatures were changed to those shown in Table 3. Note that the laminate LL7 was produced without crimping the sealant base material.

(Laminate LL13)
After forming a printed layer in the same manner as in laminate L1, adhesive T4 was used to laminate CPP with a dry laminating machine equipped with a gravure plate with a plate depth of 45 μm without interposing a polyolefin resin layer, and lamination for comparison. Body LL13 was obtained. The coating amount of the adhesive layer was 300 mg/m ² .

(Laminate LL14)
A laminate LL14 for comparison was obtained in the same manner as the laminate LL13, except that the adhesive T4 was changed to the adhesive T17. The coating weight of the adhesive layer was 2700 mg/m ² .

<Adhesive Strength of Laminate>
The obtained laminate was cut into a width of 1.5 cm, and the adhesive strength was measured by peeling at 90° with an Intesco tensile tester.
A: Adhesive strength is 1.0 N or more B: Adhesive strength is 0.6 N or more and less than 1.0 N C: Adhesive strength is 0.3 N or more and less than 0.6 N D: Adhesive strength is less than 0.3 N

Abbreviations in Tables 2 and 3 are shown below. Note that the * mark in the table is the base material recovered as the polyolefin resin.
(First base material layer)
OPP: Corona-treated biaxially oriented polypropylene film, thickness 20 μm
PET: corona-treated polyethylene terephthalate film, thickness 12 μm
Paper: Cup coated paper, 270 g/m ²
(Polyolefin resin layer)
LDPE: Novatec LD LC520 (low-density polyethylene manufactured by Japan Polyethylene Co., Ltd.)
PP: Novatec PP FL02A (polypropylene manufactured by Nippon Polyethylene)
(deposited film layer)
VMPET: aluminum-deposited polyethylene terephthalate film, thickness 12 μm
(Sealant base layer)
CPP: corona-treated unstretched polypropylene film, thickness 30 μm
VMCPP; aluminum-deposited unstretched polypropylene film, thickness 25 μm
LLDPE: corona treated linear low density polyethylene film, thickness 50 μm

Laminates LL1 to 3, 5, and 8 to LL could not be produced due to extremely low adhesive strength, and thus the subsequent separation and collection of laminates was not carried out.

<Separation and recovery of laminate>
First, the desorbing liquid used for separating and recovering the laminate was prepared by mixing under the following formulation and conditions.

Abbreviations in Table 4 are shown below.
Surfactant Y1: POE stearyl ether (POE addition number: 12, HLB value: 13.9)
Surfactant Y2: sodium lauryl sulfate (HLB value>20)
Defoamer T1: BYK-1650 (silicone emulsion manufactured by BYK-Chemie, solid content concentration 27.5%)

[Example 1]
1 kg of the desorbing liquid W1 was prepared, and 0.02 kg of the laminate L1 cut into 5 mm squares was added to the desorbing liquid. By stirring at 800 rpm for 180 minutes using a disper, the adhesive layer was released and separated between the first substrate and the LDPE. After stopping the stirring and allowing the mixture to stand still for 30 minutes, the polyolefin component (mixture of OPP and LDPE/CPP) floated due to specific gravity was scooped out with a strainer, washed with water, and dried in an oven. The remaining desorbed liquid was filtered through 80 mesh.

[Examples 2 to 35, Comparative Examples 1 to 14]
The laminate was separated and recovered in the same manner as in Example 1, except that the laminate and the desorbed liquid were changed to those shown in Table 5, and recovered polyolefin was obtained. Colored components remaining after drying were visually removed.

<Evaluation>
The separability, the degree of suspension of the desorbed liquid after separation and recovery, and the recovery rate of polyolefin were evaluated as follows.

[Separability]
In the laminated body being stirred, 10 sheets of the separated polyolefin resin or the laminated body of the polyolefin resin layer and the sealant base layer were randomly sampled at 60 minutes, 120 minutes, and 180 minutes after stirring, washed with water, and dried. The ATR-IR of the polyolefin resin surface was measured, and it was confirmed that the absorption peak of the adhesive disappeared in all 10 sheets, and evaluation was made according to the following criteria.
(Evaluation criteria)
A (excellent): disappearance of the absorption peak of the adhesive layer is confirmed after stirring for 60 minutes.
B (good): disappearance of the absorption peak of the adhesive layer is confirmed after stirring for 120 minutes.
C (acceptable): disappearance of the absorption peak of the adhesive layer is confirmed after stirring for 180 minutes.
D (improper): After stirring for 180 minutes, no disappearance of the absorption peak of the adhesive layer was observed, or the laminate did not separate and there was no transparent film to be measured.

[Turbidity of desorbed liquid]
200 ml of the desorbed liquid was collected after filtration through 80 mesh, and formazin nephelometric turbidity was measured according to JIS K0101.
(Evaluation criteria)
A (excellent): turbidity less than 50 NTU B (good): turbidity 50 NTU or more, less than 100 NTU C (acceptable): turbidity 100 NTU or more, less than 300 NTU
D (impossible) turbidity: 300 NTU or more

[Recovery rate]
The recovery rate was calculated and evaluated by the following formula.
Formula) Recovery rate (%) = mass of recovered transparent polyolefin resin/total mass of plastic components in laminate x 100
(Evaluation criteria)
A: Recovery rate is 80% or more B: Recovery rate is 50% or more and less than 80% C: Recovery rate is less than 50%

According to the above evaluation results, a laminate comprising a polyolefin resin layer in contact with an adhesive layer containing either polyethyleneimine or polybutadiene and having a coating amount of 5 to 100 mg/m ² , and a separation step and a recovery step. By combining them, it was possible to separate and recover a polyolefin resin with a small amount of adhering components while greatly reducing the suspension of the desorbed liquid. As a result, when the recovered polyolefin resin is melt-recycled, it is possible to obtain a recycled resin in which deterioration of mechanical properties and coloration are suppressed.
In particular, the application amount of the adhesive is 10 to 50 mg/m ² , the printing ink and adhesive do not contain a curing agent, and the adhesive is polyethyleneimine with a number average molecular weight of 50,000 or more and 100,000 or less. In Examples 8 to 10, 24 and 25, while exhibiting good adhesive strength, the polyolefin resin was excellent in separability, and the turbidity of the detached liquid was suppressed.
In Comparative Examples 1 and 6, in which the adhesive layer contained either polyethyleneimine or polybutadiene and the coating amount exceeded 100 mg/m ² , separation of the polyolefin resin was possible, but the released liquid was greatly suspended.
In Comparative Examples 2, 3, and 7, in which a polyurethane-based adhesive having releasability was used, the polyolefin resin could be separated, but the released liquid was remarkably suspended due to the detached adhesive component, and the adhesive layer was damaged. Even when the coating amount was 100 mg/m ² , it was highly suspended (Comparative Example 2).
Comparative laminates LL1, LL2, LL8 to LL12 lack adhesive strength, or
The polyolefin resin layer was not separated (Comparative Examples 4 and 5).

Claims (13)

A laminate comprising at least a first substrate layer, an adhesive layer containing either polyethyleneimine or polybutadiene and having a mass per unit area of 5 to 100 mg/m ² and a polyolefin resin layer in this order is removed. A method for separating and recovering a laminate, comprising: a separation step of immersing the laminate in syneresis to separate the polyolefin resin from the laminate; and a recovery step of recovering the separated polyolefin resin. The method for separating and recovering a laminate according to claim 1, wherein the laminate comprises a printed layer between the first substrate layer and the adhesive layer. 3. The method for separating and recovering a laminate according to claim 1, wherein the content of the curing agent contained in the adhesive forming the adhesive layer is 5% by mass or less based on the solid content of the adhesive. 3. The method for separating and recovering a laminate according to claim 2 , wherein the content of the curing agent contained in the printing ink forming the printing layer is 5% by mass or less based on the solid content of the printing ink. 4. The method for separating and recovering a laminate according to claim 3, wherein the content of the curing agent contained in the printing ink forming the printing layer is 5% by mass or less based on the solid content of the printing ink. 3. The method for separating and recovering a laminate according to claim 1, wherein the polyolefin resin layer is a layer formed by an extrusion lamination method. 3. The method for separating and recovering a laminate according to claim 1, wherein the adhesive layer has a mass per unit area of 10 to 50 mg/m ² . The method for separating and recovering a laminate according to claim 1 or 2, wherein the adhesive layer contains a total of 50% by mass or more of polyethyleneimine and polybutadiene based on the mass of the adhesive layer. 3. The method for separating and recovering a laminate according to claim 1, wherein the desorption liquid contains water and a surfactant. 10. The method for separating and recovering a laminate according to claim 9 , wherein the surfactant has an HLB value of 7 or more. 11. The method for separating and recovering a laminate according to claim 10 , wherein the desorbing liquid further contains an antifoaming agent having an HLB value of 1 to 3. The method for separating and recovering a laminate according to claim 1 or 2, wherein the desorbing liquid is an alkaline aqueous solution having a temperature of 40°C to 90°C and a pH of 12 or higher. 3. The method for separating and recovering a laminate according to claim 1, wherein the recovering step includes a step of sorting and recovering the separated polyolefin resin by specific gravity separation.